Question

Hi I am trying to save xml to a file and it keeps adding different character at the start of file.

Code I have is

string strCXML2;

strCXML2 = "<input type=" + "\"" + "hidden" + "\"" + " name=" + "\"" + "cxml-urlencoded" + "\"" + " value=" + "\"";
strCXML2 = strCXML2 + "<!DOCTYPE cXML SYSTEM " + "\"" + "http://xml.cxml.org/schemas/cXML/1.2.023/cXML.dtd" + "\"" + ">";

//<snip>

BinaryWriter bw5 = new BinaryWriter(File.Open(Server.MapPath("~/data/test/test19.xml"), FileMode.OpenOrCreate))   
bw5.Write(strCXML2); 
bw5.Close();

This return following file in xml “}” at start each time it is some other junk character

}<input type="hidden" name="cxml-urlencoded" value="<!DOCTYPE cXML SYSTEM "http://xml.cxml.org/schemas/cXML/1.2.023/cXML.dtd">

Any ideas why it is doing this?

Answer 1

The characters it is writing is the encoded length of the string, because: it is not expecting to write a text file. BinaryWriter writes… binary. It is writing the string in an encoded binary way that it can read back with BinaryReader.ReadString.

Instead, use just:

File.WriteAllText(path, strCXML2);

The BinaryWriter.Write(string) method’s documentation explains all this:

A length-prefixed string represents the string length by prefixing to the string a single byte or word that contains the length of that string. This method first writes the length of the string as a UTF-7 encoded unsigned integer, and then writes that many characters to the stream by using the BinaryWriter instance’s current encoding.

and, helpfully, links to a separate section about writing text files